This invention relates to thermally insulated valve actuator subassemblies and to combination HVAC valves and insulated valve actuators.
Conduit and valves used in HVAC systems frequently are thermally insulated with a wrapping material to minimize energy loss as well as inhibit condensation and corrosion. This condensation and corrosion tends to occur with refrigeration/air conditioning systems, such as those employing chilled water. Extension valve actuators to control the valves beneath the insulation extend through the thickness of the insulation to the exterior thereof where a handle is attached. On known systems, the extended actuator comprises an actuator shaft extending from the valve to the exterior handle. The shaft is of metal for torsional strength, and the handle itself is also typically of metal. Metal is normally considered necessary to provide the torsional strength needed to operate the valve. These HVAC valves typically have a so-called "memory stop," i.e., an adjustable metallic stop on the actuator which is cooperative with a fixed stop on the valve body, to control the degree of valve opening to a predetermined amount. Access to this memory stop for adjustment thereof is with a tool, typically a screwdriver, that is inserted through the insulation alongside the valve stem. Even though insulation is wrapped around the pipes and valves, the high thermal conductivity of the metal extension components, and of the memory stop components, results in cold temperatures at the exterior of the insulation, with resulting energy loss, condensation and corrosion.